.eve is not technically an extension, it's just a resource flag I allocated in my C++ server (I plan to expand it later on). But either way, I'm pretty sure that part isn't the issue. It's just that I'm not sure how to redirect the FULL request as if it were fresh from the client AFTER an error has been served by my server (or proxy, or whatever you want to call it).
Posted at Nginx Forum: http://forum.nginx.org/read.php?2,36944,36957#msg-36957